The first 20 minutes of Frank Hall Green’s debut feature, “Wildlike,” should be uncomfortable to watch—and that is putting it mildly.

The opening sequence pushes audiences to immediately root for the drama’s 15-year-old protagonist, Mackenzie, who runs away from living with her sexually abusive uncle, while longing for her struggling, absent mother, who is hundreds of miles away.

The catch, however, is that once she sets out for her home in Seattle, she is not facing a suburban trek. She is up against the Alaskan frontier, with help from none other than a reluctant, lone traveler named Bart, who is dealing with demons of his own.

Initially, the setting was much closer to the East End, where “Wildlike” will make its world premiere at the Hamptons International Film Festival on Friday, October 10, at Regal East Hampton Cinema. In fact, it was right in its backyard.

“When I was first writing this story, I had this notion I would set it out in Montauk, that Bart may be this guy who was a year-rounder, an ex-New York City resident,” Mr. Green explained last week during a telephone interview. “Then that idea died very quickly and Alaska came in.”

Mr. Green first traveled to the Alaskan frontier in 2003, and once the screenplay came to him, he visited two more times in order to trace Mackenzie’s and Bart’s path, and to learn about the state.

He quickly learned most of the land—small yet grand mountains sandwiched by glacial lakes and plains—is undeveloped. The majority of the population is concentrated in the southeast corner, a territory connected by fewer than 10 major roads, but one that is still larger than Texas. It does have its towns with grocery stores and Starbucks, he said, but just outside of them is vast wilderness.

The locals are friendly, he said, connected by a common sense of adventure and freedom. They love their guns and their salmon—two Alaskan essentials, he said—and are always prepared for a wildlife sighting. During the cast and crew’s 31-day shoot over the course of five weeks, they once saw a moose down at a bank in Anchorage.

“I think with this movie, the attraction for the crew and the cast was, ‘We’re going to Alaska,’” Mr. Green said. “If you weren’t up for that adventure, you weren’t the right person to go on the production. We covered over 3,000 miles during the shooting days alone.”

Ella Purnell, as Mackenzie, tackled the character from moment she set foot in the audition, Mr. Green said. She’s a tough actor, he said, which was key for the story she needed to tell up against a performance by Brian Geraghty of “The Hurt Locker” fame, who portrays Uncle.

“I wanted to investigate something, as a drama, that was deeper than the usual struggles. I wanted to carry a message,” Mr. Green said. “It’s just something that became incredibly important. Sexual assault can happen in a lot of different ways, and suddenly, it’s a message I couldn’t give enough.”

When Mr. Greenwood, who plays Bart, first came into production, he and the writer-director went over the script for two straight days and hatched an idea. They filmed the actor flipping through the pages, saying, “No, I’m not going to say this. That’s not going to work. That’s all got to change. That entire page has to go,” all deadpanned.

Then, they sent it to the film’s three producers. “We got the biggest kick out of it,” Mr. Green laughed, “making them think they were in for hell.”

After wrapping in Alaska in September 2012, Mr. Green drove back to New York through Canada, where he got to work on editing. There, he saw the relationship between Bart and Mackenzie grow in importance. He hadn’t fully explored the idea, he said.

“At its base, there’s this idea of longing for total acceptance by another person,” Mr. Green said of the film. “It’s easy to be alone, because there’s no risk of conflict. But at the same time, you can have this longing for someone who gives you exactly what you need. I think Bart, because he’s [disinterested] in taking on a problem, he becomes the perfect person for total acceptance. And Mackenzie, on the other hand, has never had someone caring for her the way he does.”

That was a story he had always wanted to tell, he said. He just didn’t know it at the time.

“Wildlike” will make its world premiere on Friday, October 10, at 7 p.m. at Regal East Hampton Cinema. Additional screenings will follow on Saturday, October 11, at 1:15 p.m. at Regal East Hampton Cinema and Monday, October 13, at 3 p.m. at Guild Hall in East Hampton. Tickets are $15. For more information, visit hamptonsfilmfest.org.